A novel low-loss and ultra-low temperature sinterable microwave dielectric material, AgZnVO4, was systematically investigated for the first time. The material exhibited a monoclinic structure with a space group P21/n, obtained by conventional solid-state processing. The material also showed combined microwave dielectric properties of εr = 10.3, Q×f = 42,000 GHz, and τf = –9.2 ppm/°C for specimens sintered at 540 °C. The partial substitution of Mg for Zn in the Ag(Zn1−xMgx)VO4 ceramics effectively improved the densification and reduced the dielectric loss of the ceramics. X-ray diffraction patterns revealed a single solid solution phase of Ag(Zn1−xMgx)VO4. The relative density, dielectric polarizability, packing fraction, lattice energy, and bond valence of the samples were calculated. An excellent combination of the microwave dielectric properties was obtained for Ag(Zn0.97Mg0.03)VO4 ceramic sintered at 540 °C: εr = 10.6, Q×f = 52,000 GHz, and τf = –10 ppm/°C. Additionally, the ceramic exhibited good chemical compatibility with aluminum electrodes, indicating great potential for ultra-low temperature co-fired ceramics (ULTCC) applications, particularly in the microwave and millimeter wave regions. •First systematic investigation of low-loss, ultra-low temperature sinterable AgZnVO4 microwave dielectric.•AgZn0.97Mg0.03VO4 ceramic at 540°C achieved optimized dielectric properties: εr = 10.6, Q×f = 52,000 GHz, and τf = –10 ppm/°C.•It showed great chemical compatibility with aluminum during co-firing, indicating promise for ULTCC applications.•A 5G millimeter wave patch antenna was designed for the AZMV ceramic.